1. Field of the Invention
The present invention relates to a medium-holding device, a medium-conveying device, and an inkjet recording device, and particularly to a technology for holding a sheet-shaped medium by suction on a suction-holding surface.
2. Description of the Related Art
An inkjet recording device has been known as a device for recording an image on a sheet-shaped medium. The inkjet recording device ejects and deposits ink droplets onto a medium from a nozzle provided in a head to record an image on the medium.
In the inkjet recording device, a region of the medium facing a nozzle region in the head has to be kept flat during printing. If the medium is wavy, a distance to the nozzle varies such that the ink droplet is not placed at a desired position on the medium to deteriorate image quality. For this reason, the inkjet recording device frequently employs a conveyance form of holding a medium by suction as conveying means for conveying a medium.
For example, PTL 1 (Japanese Patent Application Laid-Open No. 2010-158812) proposes that a suction pressure is varied and set for each region in order to stably hold also a stiff medium, such as thick paper, by suction. In PTL1, since the suction pressure is varied and set for each region, the suction pressure in each region is adjusted by adjusting a width, a length or the like of a suction groove connected to suction apertures provided in each region.
PTL 2 (Japanese Utility Model Laid-Open No. 1-99630) proposes that a suction pressure in each region is adjusted by making a diameter of a suction aperture in a region in which a suction pressure is to be increased larger than a diameter of a suction aperture in other region.